1. Field of the Invention
This invention relates to novel corrosion inhibiting compositions and to processes of using them. More particularly, this invention relates to novel corrosion-inhibiting compositions which reduce the attack of various aqueous fluids, including aqueous acids, alkaline solutions and heavy brines, on ferrous metals, such as iron and steel, and to processes of using such compositions.
2. Description of the Prior Art
Aqueous acids, alkaline solutions and heavy brines are known to damage ferrous metal surfaces. These corrosive substances are often found in or added to crude oils and intermediate or final products made therefrom. In addition, when exploring for and recovering petroleum from underground fields it is common to "acidize" new and producing wells with aqueous solutions of strong acids. This of course can lead to corrosion of well casings, pumps and other ferrous metal-containing equipment.
Similarly, acidic materials are often generated in equipment used in processing or transporting petroleum refinery streams, where water vapor can combine with acidic gases evolved during refinery operations to yield corrosive gases.
Various materials for inhibiting the attack of corrosive fluids on ferrous metals are known, but few provide satisfactory protection. Arsenic and various arsenic compounds, for example, have been used, notwithstanding their toxicity, as acid corrosion inhibitors for ferrous metals. However, the adverse effect arsenic and arsenic compounds have on catalysts used in petroleum refineries, coupled with their toxicity, has lead the industry to search for corrosion inhibitors which are free of such undesirable properties.